THE Technical Conference on Linux Networking

Netdev 0.1


talk | UDP encapsulation, FOU, GUE, & RCO

Tom Herbert

A discussion about recent efforts to make UDP encapsulation performant and well supported in the Linux networking stack, and also an introduction of foo-over UDP (FOU) and Generic UDP Encapsulation(GUE).

UDP based encapsulation is likely to become ubiquitous in data centers, not just for virtualization use case but also for non-virtualization. The reasons for this are simple: it's a low overhead protocol and allows us to leverage several UDP specific optimizations commonly supported by networking hardware (RSS and ECMP for instance). In part one of this this talk, we'll review the additions to the Linux kernel to make UDP encapsulation efficient and a first class citizen of the stack.

For part two of this discussion, we'll look at foo-over-UDP (FOU). FOU is an encapsulation method to where IP protocol packets are directly encapsulated in a UDP payload. The first support of this is IPIP, sit, GRE tunnels which can be configured to transmit using FOU encapsulation. The GRE part implements the GRE/UDP draft.

For part three of this discussion, we'll look at Generic UDP Encapsulation (GUE) and Remote Checksum Offload. GUE is a lightweight, extensible, and performant encapsulation mechanism of IP protocol packets (indicated in a header field). The GUE header allows for optional data fields which which we intend to use for virtualization, security, and congestion control.

slides: /docs/herbert-UDP-Encapsulation-Linux.pdf